Ice class


Ice class refers to a notation assigned by a classification society or a national authority to denote the additional level of strengthening as well as other arrangements that enable a ship to navigate through sea ice. Some ice classes also have requirements for the ice-going performance of the vessel.

Significance of ice class

Not all ships are built to an ice class. Building a ship to an ice class means that the hull must be thicker, and more scantlings must be in place. Sea chests may need to be arranged differently depending on the class. Sea bays may also be required to ensure that the sea chest does not become blocked with ice. Most of the stronger classes require several forms of rudder and propeller protection. Two rudder pintles are usually required, and strengthened propeller tips are often required in the stronger ice classes. More watertight bulkheads, in addition to those required by a ship's normal class, are usually required. In addition, heating arrangements for fuel tanks, ballast tanks, and other tanks vital to the ship's operation may also be required depending on the class.

Different ice classes

IACS Polar Class

Ships can be assigned one of seven Polar Classes ranging from PC 1 for year-round operation in all polar waters to PC 7 for summer and autumn operation in thin first-year ice based on the Unified Requirements for Polar Class Ships developed by the International Association of Classification Societies. The IACS Polar Class rules were developed to harmonize the ice class rules between different classification societies and complement the IMO Guidelines for Ships Operating in Arctic Ice Covered Waters.

Finnish-Swedish ice class

Traffic restrictions in the Baltic Sea during winter months are based on the Finnish-Swedish ice classes. These restrictions, imposed by the local maritime administrations, declare the minimum requirements for ships that are given icebreaker assistance, for example "ice class 1A, 2000 DWT".
In the Finnish-Swedish ice class rules, merchant ships operating in first-year ice in the Baltic Sea are divided into six ice classes based on requirements for hull structural design, engine output and performance in ice according to the regulations issued by the Swedish Maritime Administration and the Finnish Transport and Communications Agency. International classification societies have incorporated the Finnish-Swedish ice class rules to their own rulebooks and offer equivalent ice class notations that are recognized by the Finnish and Swedish authorities.
Ships of the highest ice class, 1A Super, are designed to operate in difficult ice conditions mainly without icebreaker assistance while ships of lower ice classes 1A, 1B and 1C are assumed to rely on icebreaker assistance. In addition there are ice class 2 for steel-hulled ships with no ice strengthening that are capable of operating independently in very light ice conditions and class 3 for vessels that do not belong to any other class such as barges. In official context and legislation, the ice classes are usually spelled with Roman numerals, e.g. IA. Classification societies may sometimes use somewhat different distinguishing marks for Finnish-Swedish ice classes; for example, 1A Super is defined as Ice Class I AA by the American Bureau of Shipping and ICE by DNV GL.

Classification societies

American Bureau of Shipping

The American Bureau of Shipping has a system of ice classes which includes classes A5 through A0; B0, C0, and D0. A5 class is the strongest built of the classes, with D0 being the weakest. All other major classification societies have a similar system of ice classes, and converting between ice classes is relatively easy. In most cases only the names of the classes are changed and the specifics of the Arctic class are identical. ABS Class A5 is the only Arctic Class that may act independently in extreme Arctic waters with no limitations. Other classes are subject to limitations on time of year, required escort and ice conditions.
The ABS database includes hundreds of Arctic Ice Classed ships, including many Arctic Research Vessels, and the entire productions of certain shipyards.

Russian Maritime Register of Shipping

The Russian Maritime Register of Shipping, established in 1913, has a long history of classing icebreakers and ice-strengthened vessels, and today maintains its own set of ice class rules for vessels navigating in freezing non-Arctic and Arctic seas. Out of about 5,000 vessels classified by the RMRS, over 3,200 are strengthened for navigation in ice and 300 of these have an ice class intended for operations in Arctic waters.
The RMRS ice class rules have been revised and the class notations changed several times over the years., the ice classes are divided to non-Arctic, Arctic and icebreaker classes. The ice class notation is followed by a number which denotes the level of ice strengthening: Ice1 to Ice3 for non-Arctic ships, Arc4 to Arc9 for Arctic ships, and Icebreaker6 to Icebreaker9 for icebreakers. These ice classes can be assigned in parallel with the Finnish-Swedish ice class and/or the IACS Polar Class, provided the vessel complies with all applicable rules. The selection of ice class is based on the operating area in the Russian Arctic, time of year, ice conditions, operating tactics, and whether the vessel operates under icebreaker escort or independently. In addition, icebreaker classes have additional requirements for minimum shaft power and icebreaking capability.

Canadian ice classes

Arctic Class

A class attributed to a vessel under the Canadian Arctic Shipping Pollution Prevention Regulations regime, which indicates that the vessel met the requirements of those regulations.
Up to December 2017, Canadian Arctic Shipping Pollution Prevention Regulations establish 9 Arctic classes for ship based on requirements for hull structural design, engine power, engine cooling water arrangement, propeller, rudder and steering gear and performance in ice.
Ice Class indexArctic ClassDescriptionCanadian Coast Guard icebreaker class
Higher10
8
7Can maintain a speed of 3 knots through ice 7 feet thick
6
4Can maintain a speed of 3 knots through ice 4 feet thickHeavy
3Can maintain a speed of 3 knots through ice 3 feet thickMedium
2Light
1A
Lower1

Canadian Arctic Class (CAC)https://www.tc.gc.ca/eng/marinesafety/tp-tp12819-menu-1338.htm [User Assistance Package for the Implementation of Arctic Ice Regime Shipping System - AIRSS (1998) - TP 12819 E]

A class attributed to a vessel under the Canada Shipping Act regime, which indicates that the vessel met the requirements of the applicable standards of TP 12260 Equivalent Standards for the Construction of Arctic Class Ships, published by the Department of Transport, on December 1, 1995.
This new system exists for determining how the most highly ice-strengthened vessels are classed by Transport Canada, Marine Safety. Four Canadian Arctic Classes have now replaced the previous Arctic 1 - Arctic 10 Classes. Details of the new structural classifications are provided in the Transport Canada publication Equivalent Standards For The Construction Of Arctic Class Ships - TP 12260E; to summarize:
Vessels CAC 1, 2, 3, and 4 may also be considered suitable escorts, capable of escorting ships of lower classes. Canada has developed structural standards for each of these classes. Ships built to polar standards of other Classification Societies and national authorities can apply for CAC equivalency on a case-by-case basis, as can owners of vessels previously classified under the existing Canadian system for Arctic Class vessels.
CategoryEquivalent Arctic Class
CAC 1→Arctic Class 10
CAC 2→Arctic Class 8
CAC 3→Arctic Class 6
CAC 4→Arctic Class 3

Note: The CAC categories are equivalent to the Arctic Classes as shown in table. These nominal equivalencies are not reciprocal.